Adaptation to Climate Change for Agriculture in The Adaptation to Climate Change for Agriculture in The Gambia: Gambia:

An explorative study on adaptation strategies for MilletAn explorative study on adaptation strategies for Millet

Dr. Momodou NjieDr. Momodou NjieBlue Gold Solutions ®, Banjul,The GambiaBlue Gold Solutions ®, Banjul,The Gambia

Bernard E. Gomez and Bubu Pateh JallowBernard E. Gomez and Bubu Pateh JallowGlobal Change Research Unit, Department of Water Resources, Global Change Research Unit, Department of Water Resources,

Banjul, The GambiaBanjul, The Gambia; ;

Molly E. HellmuthMolly E. HellmuthColumbia University, Columbia, USAColumbia University, Columbia, USA

John M. Callaway , John M. Callaway ,

UCCEE, Risoe, DenmarkUCCEE, Risoe, Denmark

Peter Droogers,Peter Droogers,Future Water, The NetherlandsFuture Water, The Netherlands

Objective of the StudyObjective of the Study

1.1. Develop and implement an analytical tool Develop and implement an analytical tool for estimating and comparing the costs and for estimating and comparing the costs and benefits of adaptation projects in the benefits of adaptation projects in the agricultural sector of the Gambia;agricultural sector of the Gambia;

2.2. Make the Tool Available to the AIACC Make the Tool Available to the AIACC Community and other interested research Community and other interested research groups;groups;

3.3. Funding provided under the AIACC Funding provided under the AIACC Project Project (UCCEE -RISOE/UCT/GCRU-(UCCEE -RISOE/UCT/GCRU-DWR)DWR)

Methodology and ToolsMethodology and Tools

The main steps were:The main steps were:

1.1. Collection of base data and information;Collection of base data and information;

2.2. Extraction of IPCC projections for The Gambia;Extraction of IPCC projections for The Gambia;

3.3. Post-processing GCM projections using downscaling of the Post-processing GCM projections using downscaling of the HadCM3 and ECHAM4 outputs;HadCM3 and ECHAM4 outputs;

4.4. Setting up an environmental and biophysical model;Setting up an environmental and biophysical model;

5.5. Evaluation of projected climate change impacts on yields;Evaluation of projected climate change impacts on yields;

6.6. Identification and selection of most appropriate adaptation Identification and selection of most appropriate adaptation strategies from the INC centered around water availability, strategies from the INC centered around water availability, nutrient availability, and water use efficiency ;nutrient availability, and water use efficiency ;

7.7. Economic evaluation of these adaptation strategies.Economic evaluation of these adaptation strategies.

The Environmental and Biophysical The Environmental and Biophysical ModelModel

This study used the coupled SWAP-WOFOST This study used the coupled SWAP-WOFOST model.model.

1.1. SWAP (Soil-Water-Atmosphere-PlantSWAP (Soil-Water-Atmosphere-Plant) ) simulates one-dimensional water, solute, and simulates one-dimensional water, solute, and heat transport in saturated and unsaturated heat transport in saturated and unsaturated soils whereas soils whereas

2.2. WOFOST (the WOrld FOod STudies modelWOFOST (the WOrld FOod STudies model) ) provides a detailed description of crop provides a detailed description of crop growth processes from emergence to growth processes from emergence to maturity. maturity.

Impact of Climate Change on Millet Impact of Climate Change on Millet ProductionProduction

1.1. Simulated millet yields (Table 1) indicate an Simulated millet yields (Table 1) indicate an increase in average yields of 2% (1,046kg/ha increase in average yields of 2% (1,046kg/ha ECHAM4) to 13% (1,141kg/ha HadCM3) in ECHAM4) to 13% (1,141kg/ha HadCM3) in the Near Futurethe Near Future

2.2. In the distance future the HadCM3 and In the distance future the HadCM3 and ECHAM4 simulations suggest average yields ECHAM4 simulations suggest average yields change of – 68 (243kg/ha) to 38% change of – 68 (243kg/ha) to 38% (1,274kg/ha) about the reference period yield (1,274kg/ha) about the reference period yield of 1,030Kg/haof 1,030Kg/ha

Identified Adaptation StrategiesIdentified Adaptation StrategiesUsing the recommendations in the Gambia’s INC (GOTG, Using the recommendations in the Gambia’s INC (GOTG,

2003) on potential adaptation measures in the 2003) on potential adaptation measures in the agricultural sector, and new insights from this study, agricultural sector, and new insights from this study, the following three adaptation strategies are explored: the following three adaptation strategies are explored:

1.1. (i) Improved crop variety(i) Improved crop variety (-14 to 13% in the near (-14 to 13% in the near future; -2 to 65% in the distance future),future; -2 to 65% in the distance future),

2.2. (ii) Enhanced use of fertiliser(ii) Enhanced use of fertiliser (33 to 39% near future (33 to 39% near future and expo. to 142% distsnt future), andand expo. to 142% distsnt future), and

3.3. (iii) Introduction of irrigation(iii) Introduction of irrigation (38 to 44% in the near (38 to 44% in the near future droping by 5% due to water logging beyond 200mm/yr future droping by 5% due to water logging beyond 200mm/yr delivery; delivery <200mm gives a 34% increase under delivery; delivery <200mm gives a 34% increase under ECHAM4; Under HadCM3 average yield increases by 214 and ECHAM4; Under HadCM3 average yield increases by 214 and 412% with delivery rate of 200 and 500 mm/yr. respectively)412% with delivery rate of 200 and 500 mm/yr. respectively)

Economic evaluation of adaptation Economic evaluation of adaptation strategiesstrategies

1.1. The economic analysis uses costs and benefits of The economic analysis uses costs and benefits of adaptation strategies within a national cereal self-adaptation strategies within a national cereal self-sufficiency/import substitution framework. sufficiency/import substitution framework.

2.2. Two responses to climate change are evaluated:Two responses to climate change are evaluated: Business as UsualBusiness as Usual Adaptation using Adaptation using IrrigationIrrigation and alternatively, and alternatively,

FertilisationFertilisation 3.3. Benefit-cost analyses undertaken consist of Benefit-cost analyses undertaken consist of

subjecting the selected adaptation strategies to subjecting the selected adaptation strategies to economic efficiency tests. economic efficiency tests.

A discount rate of 9% and a project horizon of 60 A discount rate of 9% and a project horizon of 60 years was used.years was used.

Costs are both technology- and scale-dependent, with Costs are both technology- and scale-dependent, with solar-based technology systems exhibiting the highest solar-based technology systems exhibiting the highest development cost per hectare or per cubic meter (mdevelopment cost per hectare or per cubic meter (m33) ) of water.of water.

Operation and Maintenance (O&M), and distributionOperation and Maintenance (O&M), and distribution costs represent the two largest components. costs represent the two largest components.

For both surface and groundwater, and independent For both surface and groundwater, and independent of scale, of scale, O&M and distribution account for 80 – 90%O&M and distribution account for 80 – 90% of total cost of irrigation using diesel-based water-of total cost of irrigation using diesel-based water-lifting technologies. lifting technologies.

Economic evaluation of adaptation Economic evaluation of adaptation strategies strategies (Cost Effectiveness Table 6)(Cost Effectiveness Table 6)

Economic evaluation of adaptation Economic evaluation of adaptation strategiesstrategies (Benefit-Cost Analysis Tables 7 & 8)(Benefit-Cost Analysis Tables 7 & 8)

Tables 7 and 8 Tables 7 and 8 summarisesummarise the results the results of computations based on (i) irrigation; of computations based on (i) irrigation; and its alternative (ii) fertilisation.and its alternative (ii) fertilisation.

Table 7 shows negative net benefits of Table 7 shows negative net benefits of irrigation as an adaptation option in the irrigation as an adaptation option in the near future (2010 – 2039). near future (2010 – 2039).

The net adaptation benefits (NAB) The net adaptation benefits (NAB) become positive when water cost drop become positive when water cost drop below 0.09USD/mbelow 0.09USD/m3

In contrast, In contrast, irrigation in the distant future irrigation in the distant future could be an economically efficientcould be an economically efficient adaptation measure against climate change adaptation measure against climate change losses. losses. However, such efficiency is related However, such efficiency is related to policy variables like the stock-to-to policy variables like the stock-to-utilisationutilisation (STU) ratio governing import of (STU) ratio governing import of cereals. cereals.

Imposed cost of climate change (ICCC) can Imposed cost of climate change (ICCC) can also be minimised by decreasing cereal also be minimised by decreasing cereal intakeintake from 250 kg/capita to 175 kg/capita, from 250 kg/capita to 175 kg/capita, ICCCICCC drops to USD704 million, but NAB drops to USD704 million, but NAB become negative, at an STU of 10%.become negative, at an STU of 10%.

But Increase STU and net benefit worsens But Increase STU and net benefit worsens and so and so minimisationminimisation of ICCC is not a of ICCC is not a straightforward matter.straightforward matter.

Economic evaluation of adaptation Economic evaluation of adaptation strategies strategies (Benefit-Cost Analysis Tables 7 & 8)(Benefit-Cost Analysis Tables 7 & 8)

Compared to irrigation, fertiliser applicationCompared to irrigation, fertiliser application, in Table 8, , in Table 8, becomes becomes more efficient adaptation option in the near more efficient adaptation option in the near future. future.

Adaptation benefits outweigh corresponding costs Adaptation benefits outweigh corresponding costs and cut CCD by 14 to 20%.and cut CCD by 14 to 20%.

Positive NAB into the distant futurePositive NAB into the distant future also also provides a provides a strong indication of economic viabilitystrong indication of economic viability. .

Fertilisation Fertilisation is less efficientis less efficient than irrigation under the than irrigation under the STU =10%,STU =10%, but it may be a but it may be a more prudent approach if more prudent approach if higher STU targetshigher STU targets are central to food security policy. are central to food security policy.

Economic evaluation of adaptation Economic evaluation of adaptation strategiesstrategies (Benefit-Cost Analysis Tables 7 & 8)(Benefit-Cost Analysis Tables 7 & 8)

Combine business-as-usualCombine business-as-usual (i.e., food imports) (i.e., food imports) with with fertilisation and irrigationfertilisation and irrigation of locally grown cereals. of locally grown cereals.

In particular, In particular, expanding crop fertilisation in the short-expanding crop fertilisation in the short-run has significant advantagesrun has significant advantages. . It requires no It requires no technological sophistication, and promises high returnstechnological sophistication, and promises high returns. .

Adoption of irrigation may become an imperative in Adoption of irrigation may become an imperative in the distant futurethe distant future if precipitation declinesif precipitation declines in in conformity with the HadCM3 projections conformity with the HadCM3 projections or world or world cereal markets become seriously affectedcereal markets become seriously affected by by conditions in countries with historically surplus conditions in countries with historically surplus productionproduction

Economic evaluation of adaptation Economic evaluation of adaptation strategiesstrategies (Benefit-Cost Analysis Tables 7 & 8)(Benefit-Cost Analysis Tables 7 & 8)

CONCLUSIONS OF THE STUDYCONCLUSIONS OF THE STUDY The study demonstrates that climate change impacts The study demonstrates that climate change impacts

depend on the magnitude of global warming, and statistical depend on the magnitude of global warming, and statistical moments of precipitation projected by GCM used in moments of precipitation projected by GCM used in impact analysis studies. impact analysis studies.

Out of three adaptation strategies studied, cropland Out of three adaptation strategies studied, cropland irrigation emerges as the most promising in terms of irrigation emerges as the most promising in terms of improving yields.improving yields.

However, in the near future importation of food is more However, in the near future importation of food is more cost effective because of the high unit costs of irrigation cost effective because of the high unit costs of irrigation development. development.

Relative economic performance of irrigation improves Relative economic performance of irrigation improves when water becomes a limiting crop production factor when water becomes a limiting crop production factor in the distance future (HadCM3 – distant future in the distance future (HadCM3 – distant future scenario).scenario).

It should be point out that there are some It should be point out that there are some methodological limitations. methodological limitations.

1.1. For instance, the performance of crop breeding as an For instance, the performance of crop breeding as an adaptation strategy cannot be realistically and adaptation strategy cannot be realistically and unambiguously assessed without reference to a unambiguously assessed without reference to a specific millet cultivar. specific millet cultivar.

2.2. Prediction of R&D outcomes so far into the future is Prediction of R&D outcomes so far into the future is not yet successfully celebrated. not yet successfully celebrated.

3.3. Unconditional stability of market prices for cereals Unconditional stability of market prices for cereals implied by constant prices may also require some implied by constant prices may also require some modification, possibly through interfacing the modification, possibly through interfacing the analysis with a global trade model or finding some analysis with a global trade model or finding some way of linking world market prices with national way of linking world market prices with national output.output.

CONCLUSIONS OF THE STUDYCONCLUSIONS OF THE STUDY

All things considered, there is no single out-All things considered, there is no single out-ranking adaptation strategy for agricultural ranking adaptation strategy for agricultural crop production in the future. crop production in the future.

Rather, our results indicate a combination of Rather, our results indicate a combination of business as usual with fertilisation, in the near business as usual with fertilisation, in the near future, and irrigation in distant future, as the future, and irrigation in distant future, as the best way forward. best way forward.

CONCLUSIONS OF THE STUDYCONCLUSIONS OF THE STUDY

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